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OCR Chemistry F322~ 4th June 2013~ AS Chemistry

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Can someone explain 6 c i on June 2010? Thanks :smile:
Can anybody help me with the calculation in Question 3 (d) of this paper, it seems different to a normal % yield question.

Any help appreciated. :smile: :smile:

http://www.ocr.org.uk/Images/131287-question-paper-unit-f322-chains-energy-and-resources.pdf
guys for the questions that say write the equation for the oxidation reaction. is it just [o] for aldehydes and ketones and 2[o] for carboxys. then the product is always just one mole of what was being formed
Reply 1963
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ssflcb
12
Original post by needtosucceed=)
its in the first post of this thread :smile:


Thank you :smile:
Reply 1964
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Namod
10
Hello, i'm retaking this unit,
and didn't do any F322 for 1 full year.
Still didn't do any paper or anything, I'm thinking of starting my revision now.
People say in this case do "cramming", what is cramming so I can do it?

EDIT: Searched in google, understood it but the question is now does it work?
(edited 10 years ago)
Original post by flygerianmc
guys for the questions that say write the equation for the oxidation reaction. is it just [o] for aldehydes and ketones and 2[o] for carboxys. then the product is always just one mole of what was being formed


Yeah!
Original post by flygerianmc
guys for the questions that say write the equation for the oxidation reaction. is it just [o] for aldehydes and ketones and 2[o] for carboxys. then the product is always just one mole of what was being formed


yep one mole of your product.yep thats correct. and waters formed
Reply 1967
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wndms
1
What are the conditions for hydrogenation??

Posted from TSR Mobile
Original post by the A* guy
Can anybody help me with the calculation in Question 3 (d) of this paper, it seems different to a normal % yield question.

Any help appreciated. :smile: :smile:

http://www.ocr.org.uk/Images/131287-question-paper-unit-f322-chains-energy-and-resources.pdf


do the normal actual/theoretical

then if u look at the equation its not a 1:1 ratio of methane:hydrogen

so scale it up by either multiplying the methane moles by 3 or dividing the hydrogen moles by 3
Original post by needtosucceed=)
yep one mole of your product.yep thats correct. and waters formed


ty :tongue:
Original post by wndms
What are the conditions for hydrogenation??

Posted from TSR Mobile


Nickel catalyst, 523 K and high pressure.
Original post by wndms
What are the conditions for hydrogenation??

Posted from TSR Mobile


nickel catalyst. 300oc
This sounds really silly...

BUT
I always forget which way equilibriums shift :'( and i just can't seem to remember... :angry:
Reply 1973
Avatar for Namod
Namod
10
Hello, i'm retaking this unit,
and didn't do any F322 for 1 full year.
Still didn't do any paper or anything, I'm thinking of starting my revision now.
People say in this case do "cramming", but the question is now does "cramming" work?
Original post by danlocke
Can someone explain 6 c i on June 2010? Thanks :smile:


deltaH = q x n, rearrange this equation is q = deltaH x n

divide the enthalpy change given in the equation by 4 because you want 1 mole of it, but that enthalpy change is for 4 moles

then multiply this answer by 2.5x10^5
Original post by Blashnet
Hey!

I got 49/60 unit one (72 ums) and 37/40 in pracs (dont know what UMS)

Anyone got any idea of what raw/ums mark i'd need for an A?


112
Original post by Blashnet
This sounds really silly...

BUT
I always forget which way equilibriums shift :'( and i just can't seem to remember... :angry:


increase temp = shift in the endothermic direction
decrease temp = shift in the exothermic direction

increase pressure = shifts to side with fewer moles of gas
decrease pressure = shifts to side with more moles of gas

the opposite occurs for each change,
Reply 1977
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Kits
10
Original post by needtosucceed=)
lol fair enough. you should be fine if you scrape an A, ur practicals are high


Niceeeeeee
Original post by Blashnet
This sounds really silly...

BUT
I always forget which way equilibriums shift :'( and i just can't seem to remember... :angry:


I swear I gave a good method time but here it is again

I just remember t as if it exothermic in foward direction (- delta H)

Increase temp shifts to left (EXIL)
Decrease temp shifts right. (EXDR)

If its endothermic in foward direction (+ delta H)
Increase temp shifts to the right (ENIR)
Decrease temp shifts to the left (ENDL)

Stupid method put that's how I remember for temperture

As for pressure

Ch4 + br2-----> 4ch3br
Increase pressure shifts to side with fewer moles ( so in this reaction left as it has 2 moles)

Decrease pressure shifts to side with more moles (so in this case the right as there 4 moles)

*only use pressure if has a gas (g) symbol on all products and reactants


My weird methods of remembering things
Reply 1979
Avatar for Namod
Namod
10
First post of 100 page I would like to thank everybody for reading this.
Anyways back to topic, does cramming work or not?

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